Diagnosing a randomly changing patch in a VST instrument

This is going to be a somewhat random post but I want to record this before I forget what I just found out.

I was playing around with Arturia’s CS80V when the patch I was playing suddenly changed: the release time increased. Also I could see the patch had changed because an asterisk appears in the patch name.

I reset the patch by selecting it in the browser, and continued playing. Suddenly, it happened again!

This time I watched the GUI of the synth to see if I could see it happen:

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Sure enough, about a minute later the patch changed sounds and something caught my eye – a slider had changed positions:

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Moving the slider back restored the original sound (although of course, the patch was still “changed” as far as the environment was concerned).

OK, how to diagnose this? I’ll cut a long story short and say eventually I set a track to record MIDI data from my controller, in case something funky was entering the MIDI event stream, and played a few notes.

A short time later, I had this:

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Those vertical lines are Continuous Controller (CC) events:

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I was recording on Track 2 and that’s three events for Continuous Controller 83 that I can’t explain.

I need to find out why my Roland A80 master keyboard is emitting these controller events. Is this new behavior, or has it always happened?

Normally they are harmless, I guess, but the default MIDI Controller mapping for CS80v  has CC# 83 mapped to this VCA envelope release time slider:

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So that explains the phantom finger on the slider. The ones in RED have been set to respond to a specific CC#.

It’s easy enough to fix – we can use the MIDI Mapping feature in Arturia’s software instruments to load an “empty” controller mapping:

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Now the patch remains unchanged even when I play back the track containing the controller data.

Next up, find out why the A80 is emitting those random controller values...

Another Way to Skin an FX Send

Modern digital audio workstations offer a plethora of ways to solve your mixing and routing problems. Inspired somewhat by Craig Anderton’s latest column in Sound on Sound, I discovered a new way to apply reverb selectively to multiple tracks, in Cakewalk By BandLab using the Sonitus Reverb VST. Here’s my use case:

I have Lead and Backing vocal tracks, and I want to apply a long-tail reverb to portions of the verse and chorus phrases. (The main sustained notes provide a wash of reverb in the background, but keeping it clean and un-muddled by fricatives and fast syllables.)

In the past I have created a “VOX FX” Buss, put an instance of Sonitus Reverb on it, and directed it to feed the “VOX” main buss. Finally, I add a Send on each vocal track to feed the VOX FX, and use “Send Level” automation on each track:

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This works well, and allows the automation curves to be adjusted per-track.

But what if you have more than two tracks, and per-track envelopes isn’t needed? Could there be a way to send audio to the reverb using a single automation curve? I experimented with using an Aux track, intending to add a send on each vocal track to the Aux track, then use the “Automated Send To FX Buss” trick described above.

However, I realized that I could simplify things by putting the reverb effect on the Aux track itself, and then automating the “VST Input Level” instead:

From the Edit Filter selector (displaying “Clips” by default) we can drill down into the Sonitus Reverb and select “Input” from the automation choices:

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Now we can draw the automation envelope (only one is needed) to control the amount of audio from all tracks being processed by the reverb:

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This gets the job done, and no need for a general purpose fx buss.

As I mentioned above, there are good reasons NOT to do it this way – but it is nice to have the option.

UPDATED 27 Sep 2019

It seems you can’t “freeze” an AUX track, so if you find yourself in the resource crunch and the FX bin on the Aux track is CPU-heavy, well, that’s another good reason not to use this technique.